Patent EA-002624-B1 (EA)
Title: Method for changing permeability of productive layer n the filter-by zone of chinks
Inventor: KALMYKOV ALEXANDR YURIEVICH
IPC: E21B36/04
Filed: 2001-05-28
Abstract: 1. A method of changing the permeability of a productive layer in the filter-by zone of the chink comprising the influence on the filter-by zone, at least, of one chink by A.C., characterixed in that the influence is carried out by the passage of different-polar packs of unipolar impulses of an electric current with pauses between positive and negative packs of impulses through the filter-by zone of a chink, and the value of the current strength of each impulse is set to be sufficient to change the permeability of a productive layer in the filter-by zone of a chink either as by the discolmatation or as by gas colmatation of water pores and capillaries, and the way of motion of unipolar impulses in a pack also determines the way of change of permeability of the filter-by zone of a chink to water, thus the period of motion of T impulses in a pack defines from an expression:   where  R3 - resistance of grounding of an electrode, ohm; h - productive bed thickness, m; ρn-a specific electrical resistance of a layer, an ohm. M; le, and re - length and radius of an electrode respectively , m; Lab - distance between electrodes, m; εr- relative dielectric permeability of a layer, tgδ - a tangent of a corner of dielectric losses, c - speed of light in vacuum, m/sec, for decreasing the permeability of the filter-by zone, the duration of ( impulses should be sufficient to provide the gas colmatation of pores and capillaries and positive value of temperature's gradient during the influence, the increase of permeability of the fiter-by zone of a chink is carried out at the variable duration of unipolar impulses in a pack, that are changed from Tmax to Tmin with the change of Δτ duration, wherein the values of τmax, τmin and Δτ should be sufficient to provide the discolmatation of pores and capillaries of the filter-by zone and zero value of temperature's gradient to the moment of the ending of each pack of impulses. 2. The method of claim 1, characterized in that during the operation, the temperature is controlled by a thermometer, which is placed in a filter of a chink, and, if necessary, the parameters of packs of impulses are being corrected. 3. The method of any of claims 1 or 2, characterized in that the duration of different-polar packs of unipolar impulses is set equal, but not more than 500 milliseconds, and the duration of a pause between packs is set equal to the difference of period of motion of impulses and the duration of the first impulse of a pack. 4. The method of any of claims 1 to 3, characterized in that the value of the current strength of each impulse should be sufficient to change the permeability of a productive layer in the filter-by zone of chinks, either as by the discolmatation, or by the gas colmatation of water pores and capillaries, the value is defined from an expression:   where rb - the radius of influence determined by logging, m; Cn - coefficient of a thermal conductivity of a layer, J/m sec, C degree ; T - permissible temperature of stratum's liquids during the influence, C degree ; Tn - temperature of a layer prior to the influence, C degree ; ς - distance from the point of connection to a working electrode to the bottom of the filter-by zone to which electrical contact is provided, m; λ - coefficient of a layeranisotropy; l- distance passed by electric current between points of connection to electrodes; h -thickness of a productive layer, m; R3- grounding resistance of an electrode (ohm). 5. The method of any of claims 1 to 4, characterized in that during the process of the influence, the values of an average current of a pack and the duration of a trailing edge of the last impulse in the pack are controlled to determine the moment of the ending of influence, the gas colmatation is stopped at spontaneous decreasing the value of an average current of a pack, at least, by 10% and increasing of the controlled duration of a back front to maximum value, and discolmatation is stopped at spontaneous increasing of value of an average current of a pack, at least, by 10% and the decreasing of the controlled duration of a trailing edge to minimum value, if the controllable parameters maintain the achieved values for at least 4 hours.